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Foundation Height

If we could conjure up the spirits of several custom home builders who have been dead for about 100 years, I am afraid they would be most disappointed. No doubt they would shake their heads when they gazed upon house after house in the suburbs that had the top of their foundations skimming just above the final grade of the soil that surrounds each house. In fact, we might even hear them mutter, "What was that builder thinking..."

If you are in the planning stages of building your new home and/or are talking to various custom home builders about a new home, you need to talk about foundation heights. This topic simply deals with the distance from the top of the foundation down to the finished grade that touches up against the foundation and the soil within 10 feet of the foundation. It may not seem important to you now, but once you are moved in and it rains hard for several days, you will wish foundation height would have been just above "How big will my kitchen be?" on your top ten wish list.

I am constantly amazed at the intelligence of many old builders who have departed this world. It is indeed a shame more builders do not "build them like they used to". Drive around the older sections of your city and you will undoubtedly see homes where the first floor level is two or even three feet above the ground outside the home. Often these homes have steps that lead up to the front door. They often have dramatic front porches where you can sit and gaze down upon the gorgeous neighborhood.

I firmly believe this was done for several reasons. Powered excavating equipment was not available or readily available. It was less expensive to dig shallower foundations. Foundation walls that protruded above grade allowed basement windows to exist without the modern sunken semi-circular window wells. These exposed windows could let in more light and ventilation into the basement. The dirt removed from the excavation could be gently graded away from the house to create wonderful positive drainage.

But scan the new homes in subdivisions today and you will rarely see a home built this way. Is the new method better? I think it is debatable, especially in light of the modern uniform building codes. The codes speak to foundation heights. Typically they say the amount of exposed foundation should be between a minimum of 4 and 6 inches above the finished soil that touches up against the foundation.

Furthermore, the code will often state the ground around the foundation must slope away from the house. Read this code section and it will almost always say the ground must fall 6 inches vertically for the first ten feet of horizontal distance away from the foundation. What do all of these numbers have to do with foundation height you might ask? Plenty!

The developer of a subdivision establishes the finish grade of the lots before construction begins. Builders need to be sensitive to these established grades. A good builder determines the highest point of ground near the home and sets the top of the foundation in relation to this high point. Keep in mind the distances stated in the building code are acceptable minimum standards. In other words, meeting the code standard is like getting a 70 percent on a test. You just barely passed. If you want an A plus on your foundation height, make sure your builder sets it higher out of the ground.

When a new home builder decides to set the foundation height too low, all sorts of problems happen. The ground around the home tends to be very flat. Positive drainage is either minimal or may not meet code. Sidewalks leading from driveways to the front door act as dams. These sidewalks become a barrier to establishing the needed positive drainage away from the house as they sit too high. The problem gets even worse when the landscapers show up. They will often mulch in these areas and create negative drainage. The water in some areas around your home may actually drain towards the foundation!

Typically, I would set all of my foundation heights about two feet higher than the highest point of grade within ten feet of the finished foundation. Doing this allowed me to create 14 or more inches of fall within the first ten feet of horizontal distance. It also produced 10 inches of exposed foundation above the soil around the home. In addition, I would use some of the excavated soil to create gentle slopes away from the house in as many directions as possible. When done properly, these slopes did not interfere with the grade established by the developer.

Houses built in this fashion do not appear to sit high out of the ground. They appear stately as they sit on the artificial rise. What's more, the house sports positive drainage from all sides so that flooding rains do not inundate the basement space.

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One Response to Foundation Height

  1. I have an exsiting brick cape-style home (built in 1948) that has a problem with raised grading and flower beds against the home's exterior, that is as high as 1-3 bricks high, above the top of the foundation walls. The home was custom built by it's original owners and I have no idea if they even knew to apply any waterproofing to the exterior of the foundation walls. The recommendation of a 4-6 inch exposed top foundation might be acheivable for the front and sides of my home, but the back has a gentle slope towards the house that I'm already too low where the grade meets the house. Can I just simply pull about 12" of the top layer away from the back of my home and apply waterproofing, so I can continue to keep the grad level 3-4 bricks high above the top of the foundation wall? Or do I really need to try to get the rear of my home excavated down to at least the 4" minimum of exposed foundation? Note: I also plan to install french drains across the back and down the sides of my home (as close the the house as I can manage) and also connect my downspouts to them as well, and run them out to the street in front of my home. Thanks for your help and advise!

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